Lithium amide

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Lithium amide
Unit cell of LiNH2.png
__ Li +
     __ N 3−
     __ H +
Names
IUPAC name
Lithium amide
Other names
Lithium azanide
Lithamide
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.029.062 OOjs UI icon edit-ltr-progressive.svg
PubChem CID
UNII
  • InChI=1S/Li.H2N/h;1H2/q+1;-1 Yes check.svgY
    Key: AFRJJFRNGGLMDW-UHFFFAOYSA-N Yes check.svgY
  • InChI=1/Li.H2N/h;1H2/q+1;-1
    Key: AFRJJFRNGGLMDW-UHFFFAOYAO
  • [Li+].[NH2-]
Properties
LiNH2
Molar mass 22.96 g·mol−1
Appearancewhite solid
Density 1.178 g/cm3
Melting point 375 °C (707 °F; 648 K)
Boiling point 430 °C (806 °F; 703 K) decomposes
reacts
Solubility slightly soluble in ethanol
insoluble in ammonia
Thermochemistry
-182 kJ/mol
Hazards
NFPA 704 (fire diamond)
NFPA 704.svgHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilInstability 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g. white phosphorusSpecial hazard W: Reacts with water in an unusual or dangerous manner. E.g. sodium, sulfuric acid
3
1
2
W
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Lithium amide or lithium azanide is an inorganic compound with the chemical formula LiNH2. It is a white solid with a tetragonal crystal structure. [1] Lithium amide can be made by treating lithium metal with liquid ammonia: [2]

Contents

2 Li + 2 NH3 → 2 LiNH2 + H2

Other lithium amides

The conjugate bases of amines are known as amides. Thus, a lithium amide may also refer to any compound in the class of the lithium salt of an amine. These compounds have the general form LiNR2, with the chemical lithium amide itself as the parent structure. Common lithium amides include lithium diisopropylamide (LDA), lithium tetramethylpiperidide (LiTMP), and lithium hexamethyldisilazide (LiHMDS). They are produced by the reaction of Li metal with the appropriate amine:

2 Li + 2 R2NH → 2 LiNR2 + H2

Lithium amides are very reactive compounds. Specifically, they are strong bases.

Examples

Lithium tetramethylpiperidide has been crystallised as a tetramer. [3] On the other hand, the lithium derivative of bis(1-phenylethyl)amine crystallises as a trimer: [4]

Tetrameric lithium tetramethylpiperidide Lithium tetramethylpiperide tetramer.jpg
Tetrameric lithium tetramethylpiperidide
Trimeric lithium bis(1-phenylethyl)amide Trimerliamide.jpg
Trimeric lithium bis(1-phenylethyl)amide

It is also possible to make mixed oligomers of metal alkoxides and amides. [5] These are related to the superbases, which are mixtures of metal alkoxides and alkyls. The cyclic oligomers form when the nitrogen of the amide forms a sigma bond to a lithium, while the nitrogen lone pair binds to another metal centre.

Other organolithium compounds (such as BuLi) are generally considered to exist in and function via high-order, aggregated species.

See also

Related Research Articles

In chemistry, amines are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia, wherein one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group. Important amines include amino acids, biogenic amines, trimethylamine, and aniline. Inorganic derivatives of ammonia are also called amines, such as monochloramine.

<span class="mw-page-title-main">Amide</span> Organic compounds of the form RC(=O)NR′R″

In organic chemistry, an amide, also known as an organic amide or a carboxamide, is a compound with the general formula R−C(=O)−NR′R″, where R, R', and R″ represent any group, typically organyl groups or hydrogen atoms. The amide group is called a peptide bond when it is part of the main chain of a protein, and an isopeptide bond when it occurs in a side chain, such as in the amino acids asparagine and glutamine. It can be viewed as a derivative of a carboxylic acid with the hydroxyl group replaced by an amine group ; or, equivalently, an acyl (alkanoyl) group joined to an amine group.

<span class="mw-page-title-main">Lithium aluminium hydride</span> Chemical compound

Lithium aluminium hydride, commonly abbreviated to LAH, is an inorganic compound with the chemical formula Li[AlH4] or LiAlH4. It is a white solid, discovered by Finholt, Bond and Schlesinger in 1947. This compound is used as a reducing agent in organic synthesis, especially for the reduction of esters, carboxylic acids, and amides. The solid is dangerously reactive toward water, releasing gaseous hydrogen (H2). Some related derivatives have been discussed for hydrogen storage.

<span class="mw-page-title-main">Organolithium reagent</span> Chemical compounds containing C–Li bonds

In organometallic chemistry, organolithium reagents are chemical compounds that contain carbon–lithium (C–Li) bonds. These reagents are important in organic synthesis, and are frequently used to transfer the organic group or the lithium atom to the substrates in synthetic steps, through nucleophilic addition or simple deprotonation. Organolithium reagents are used in industry as an initiator for anionic polymerization, which leads to the production of various elastomers. They have also been applied in asymmetric synthesis in the pharmaceutical industry. Due to the large difference in electronegativity between the carbon atom and the lithium atom, the C−Li bond is highly ionic. Owing to the polar nature of the C−Li bond, organolithium reagents are good nucleophiles and strong bases. For laboratory organic synthesis, many organolithium reagents are commercially available in solution form. These reagents are highly reactive, and are sometimes pyrophoric.

<span class="mw-page-title-main">Imide</span> Class of chemical compounds

In organic chemistry, an imide is a functional group consisting of two acyl groups bound to nitrogen. The compounds are structurally related to acid anhydrides, although imides are more resistant to hydrolysis. In terms of commercial applications, imides are best known as components of high-strength polymers, called polyimides. Inorganic imides are also known as solid state or gaseous compounds, and the imido group (=NH) can also act as a ligand.

<span class="mw-page-title-main">Lithium diisopropylamide</span> Chemical compound

Lithium diisopropylamide is a chemical compound with the molecular formula LiN(CH 2)2. It is used as a strong base and has been widely utilized due to its good solubility in non-polar organic solvents and non-nucleophilic nature. It is a colorless solid, but is usually generated and observed only in solution. It was first prepared by Hamell and Levine in 1950 along with several other hindered lithium diorganylamides to effect the deprotonation of esters at the α position without attack of the carbonyl group.

<span class="mw-page-title-main">Amidine</span> Organic compounds

Amidines are organic compounds with the functional group RC(NR)NR2, where the R groups can be the same or different. They are the imine derivatives of amides (RC(O)NR2). The simplest amidine is formamidine, HC(=NH)NH2.

<span class="mw-page-title-main">Lithium tetramethylpiperidide</span> Chemical compound

Lithium tetramethylpiperidide is a chemical compound with the molecular formula LiC9H18N. It is used as a non-nucleophilic base, being comparable to LiHMDS in terms of steric hindrance.

<span class="mw-page-title-main">Hexamethylphosphoramide</span> Chemical compound

Hexamethylphosphoramide, often abbreviated HMPA, is a phosphoramide (an amide of phosphoric acid) with the formula [(CH3)2N]3PO. This colorless liquid is a useful reagent in organic synthesis.

<span class="mw-page-title-main">Lithium bis(trimethylsilyl)amide</span> Chemical compound

Lithium bis(trimethylsilyl)amide is a lithiated organosilicon compound with the formula LiN(Si(CH3)3)2. It is commonly abbreviated as LiHMDS or Li(HMDS) (lithium hexamethyldisilazide - a reference to its conjugate acid HMDS) and is primarily used as a strong non-nucleophilic base and as a ligand. Like many lithium reagents, it has a tendency to aggregate and will form a cyclic trimer in the absence of coordinating species.

<span class="mw-page-title-main">PMDTA</span> Chemical compound

PMDTA (N,N,N,N,N-pentamethyldiethylenetriamine) is an organic compound with the formula [(CH3)2NCH2CH2]2NCH3. PMDTA is a basic, bulky, and flexible, tridentate ligand that is a used in organolithium chemistry. It is a colorless liquid, although impure samples appear yellowish.

Organosodium chemistry is the chemistry of organometallic compounds containing a carbon to sodium chemical bond. The application of organosodium compounds in chemistry is limited in part due to competition from organolithium compounds, which are commercially available and exhibit more convenient reactivity.

<span class="mw-page-title-main">Metal bis(trimethylsilyl)amides</span>

Metal bis(trimethylsilyl)amides are coordination complexes composed of a cationic metal M with anionic bis(trimethylsilyl)amide ligands (the N 2 monovalent anion, or −N 2 monovalent group, and are part of a broader category of metal amides.

<span class="mw-page-title-main">Metal amides</span>

Metal amides (systematic name metal azanides) are a class of coordination compounds composed of a metal center with amide ligands of the form NR2. Amido complexes of the parent amido ligand NH2 are rare compared to complexes with diorganylamido ligand, such as dimethylamido. Amide ligands have two electron pairs available for bonding.

<span class="mw-page-title-main">Lithium imide</span> Chemical compound

Lithium imide is an inorganic compound with the chemical formula Li2NH. This white solid can be formed by a reaction between lithium amide and lithium hydride.

Nickel compounds are chemical compounds containing the element nickel which is a member of the group 10 of the periodic table. Most compounds in the group have an oxidation state of +2. Nickel is classified as a transition metal with nickel(II) having much chemical behaviour in common with iron(II) and cobalt(II). Many salts of nickel(II) are isomorphous with salts of magnesium due to the ionic radii of the cations being almost the same. Nickel forms many coordination complexes. Nickel tetracarbonyl was the first pure metal carbonyl produced, and is unusual in its volatility. Metalloproteins containing nickel are found in biological systems.

<span class="mw-page-title-main">Tris(trimethylsilyl)amine</span> Chemical compound

Tris(trimethylsilyl)amine is the simplest tris(trialkylsilyl)amine which are having the general formula (R3Si)3N, in which all three hydrogen atoms of the ammonia are replaced by trimethylsilyl groups (-Si(CH3)3). Tris(trimethylsilyl)amine has been for years in the center of scientific interest as a stable intermediate in chemical nitrogen fixation (i. e. the conversion of atmospheric nitrogen N2 into organic substrates under normal conditions).

<span class="mw-page-title-main">Azanide</span> Anion derived from deprotonation of ammonia

Azanide is the IUPAC-sanctioned name for the anion NH−2. The term is obscure; derivatives of NH−2 are almost invariably referred to as amides, despite the fact that amide also refers to the organic functional group –C(=O)−NR2. The anion NH−2 is the conjugate base of ammonia, so it is formed by the self-ionization of ammonia. It is produced by deprotonation of ammonia, usually with strong bases or an alkali metal. Azanide has a H–N–H bond angle of 104.5°.

In chemistry, ammonolysis (/am·mo·nol·y·sis/) is the process of splitting ammonia into . Ammonolysis reactions can be conducted with organic compounds to produce amines (molecules containing a nitrogen atom with a lone pair, :N), or with inorganic compounds to produce nitrides. This reaction is analogous to hydrolysis in which water molecules are split. Similar to water, liquid ammonia also undergoes auto-ionization, , where the rate constant is k = 1.9 × 10-38.

<span class="mw-page-title-main">Amide (functional group)</span>

In chemistry, the term amide ( or or ) is a compound with the functional group RnE(=O)xNR2, where n and x may be 1 or 2, E is some element, and each R represents an organic group or hydrogen. It is a derivative of an oxoacid RnE(=O)xOH with an hydroxy group –OH replaced by an amine group –NR2.

References

  1. David, William I. F.; Jones, Martin O.; Gregory, Duncan H.; Jewell, Catherine M.; Johnson, Simon R.; Walton, Allan; Edwards, Peter P. (2007-02-01). "A Mechanism for Non-stoichiometry in the Lithium Amide/Lithium Imide Hydrogen Storage Reaction". Journal of the American Chemical Society. 129 (6): 1594–1601. doi:10.1021/ja066016s. ISSN   0002-7863. PMID   17243680.
  2. P. W. Schenk (1963). "Lithium amide". In G. Brauer (ed.). Handbook of Preparative Inorganic Chemistry, 2nd Ed. Vol. 1. NY, NY: Academic Press. p. 454.
  3. M.F. Lappert; M.J. Slade; A. Singh; J.L. Atwood; R.D. Rogers; R. Shakir (1983). "Structure and reactivity of sterically hindered lithium amides and their diethyl etherates: crystal and molecular structures of [Li{N(SiMe3)2}(OEt2)]2 and tetrakis(2,2,6,6-tetramethylpiperidinatolithium)". Journal of the American Chemical Society . 105 (2): 302–304. doi:10.1021/ja00340a031.
  4. D.R. Armstrong; K.W. Henderson; A.R. Kennedy; W.J. Kerr; F.S. Mair; J.H. Moir; P.H. Moran; R. Snaith (1999). "Structural studies of the chiral lithium amides [{PhC(H)Me}2NLi] and [PhCH2{PhC(H)Me}NLi·THF] derived from α-methylbenzylamine". Dalton Transactions: 4063–4068. doi:10.1039/A904725E.
  5. K.W. Henderson, D.S. Walther & P.G. Williard (1995). "Identification of a Unimetal Complex of Bases by 6Li NMR Spectroscopy and Single-Crystal Analysis". Journal of the American Chemical Society . 117 (33): 8680–8681. doi:10.1021/ja00138a030.